This relates generally to electronic devices with displays and, more particularly, to electronic devices with displays having efficient methods of converting from an input color space such as a red-green-blue (RGB) color space to an output color space such as a red-green-blue-white (RGBW) color space.
Electronic devices such as computers, media players, cellular telephones, set-top boxes, and other electronic equipment are often provided with displays for displaying visual information.
Displays such as organic light-emitting diode (OLED) displays and liquid crystal displays typically include an array of display pixels. Each display pixel may include one or more colored subpixels for displaying color images. In some types of displays, each display pixel includes a red subpixel, a green subpixel, a blue subpixel, and a white subpixel. These types of displays are sometimes referred to as RGBW displays.
Electronic devices having displays typically generate pixel values for the display in an RGB color space. Electronic devices having RGBW displays are therefore required to convert the pixel values from an RGB input color space to an RGBW output color space.
In conventional electronic devices, converting display data from an RGB input color space to an RGBW output color space is achieved by first transforming RGB pixel values in the RGB color space to XYZ tristimulus values in a device-independent color space. The XYZ tristimulus values in the device-independent color space are then transformed into RGBW pixel values in an RGBW color space.
The mathematical operations involved in transforming XYZ tristimulus values to RGBW pixel values can be complicated and performing such operations on-the-fly can be undesirably inefficient. The operations may involve equations that have no solution or that have multiple solutions. Additional gamut mapping may be required to obtain RGBW pixel values that produce the desired color on the display.
It would therefore be desirable to be able to provide improved ways of displaying images on displays such as RGBW displays.